The purpose of this work is to determine the enzymatic defect responsible for the various forms of glycogen storage diseases and other congenital diseases related to carbohydrate metabolism. Research will be continued in two directions: 1. Biopsies from patients will be analysed on the point of view of enzymatic activities and some of them will also be examined with the electron microscope. 2. The regulation of liver glycogen metabolism and of gluconeogenesis by glucose, insulin, adrenergic agents, glucocorticoids and cyclic AMP will be further investigated. 3. In relation with the effect of fructose on the catabolism of adenine nucleotides, several hypotheses on the origin of hyperuricemia will be tested.